The acceleration and inhibition of migration of human leucocytes in vitro by plasma protein fractions

Genetic manipulation of PLB-985 cells and quantification of chemotaxis using the underagarose assay

Neutrophils are the most common leukocyte in human blood and are the first cells to respond to injury and infection. Improper neutrophil chemotaxis can have deleterious effects on human health, including autoimmune diseases, poor innate immune response, and cancer. Therefore, gaining a better understanding of the signaling pathways governing chemotactic responses in these cells is important. One of the main challenges of working with primary human neutrophils is their short lifespan (about 1 day), making genetic manipulations not feasible. PLB-985 cells, which are pluripotent hematopoietic cells that can easily be differentiated to neutrophil-like cells, are amenable to genetic manipulations, including the expression of fluorescently tagged proteins-of-interest (POI) and gene editing using the CRISPR/CAS9 system to delete genes-of-interest (GOI). The use of PLB-985 cells can therefore greatly facilitate our understanding of the molecular mechanisms governing neutrophil biology during chemotaxis and serve as a good system to complement results gained from pharmacological inhibition of primary neutrophils. To better study the role and localization of proteins during chemotaxis, the underagarose assay has become a widely used and quantitative assay for measuring several aspects of chemotaxis. The objective of this chapter is to provide protocols for (1) the generation of genetically altered PLB-985 cell lines, (2) the set-up of an underagarose chemotaxis assay, and (3) the analysis of cell movement in chemotactic gradients from an underagarose experiment.

In vitro cell migration and invasion assays

Determining the migratory and invasive capacity of tumor and stromal cells and clarifying the underlying mechanisms is most relevant for novel strategies in cancer diagnosis, prognosis, drug development and treatment. Here we shortly summarize the different modes of cell travelling and review in vitro methods, which can be used to evaluate migration and invasion. We provide a concise summary of established migration/invasion assays described in the literature, list advantages, limitations and drawbacks, give a tabular overview for convenience and depict the basic principles of the assays graphically. In many cases particular research problems and specific cell types do not leave a choice for a broad variety of usable assays. However, for most standard applications using adherent cells, based on our experience we suggest to use exclusion zone assays to evaluate migration/invasion. We substantiate our choice by demonstrating that the advantages outbalance the drawbacks e.g. the simple setup, the easy readout, the kinetic analysis, the evaluation of cell morphology and the feasibility to perform the assay with standard laboratory equipment. Finally, innovative 3D migration and invasion models including heterotypic cell interactions are discussed. These methods recapitulate the in vivo situation most closely. Results obtained with these assays have already shed new light on cancer cell spreading and potentially will uncover unknown mechanisms.

Image-based analysis of primary human neutrophil chemotaxis in an automated direct-viewing assay

Multi-well assays based on the Boyden chamber have enabled highly parallel studies of chemotaxis-the directional migration of cells in response to molecular gradients-while direct-viewing approaches have allowed more detailed questions to be asked at low throughput. Boyden-based plates provide a count of cells that pass through a membrane, but no information about cell appearance. In contrast, direct-viewing devices enable the observation of cells during chemotaxis, which allows measurement of many parameters including area, shape, and location. Here we show automated chemotaxis and cell morphology assays in a 96-unit direct-viewing plate. Using only 12000 primary human neutrophils per datum, we measured dose-dependent stimulation and inhibition of chemotaxis and quantified the effects of inhibitors on cell area and elongation. With 60 parallel conditions we demonstrated 5-fold increase in throughput compared to previously reported direct-viewing approaches.

Measuring chemotaxis and chemokinesis: the under-agarose cell migration assay

Chemotaxis is the primary mechanism by which cell movements are directed within multicellular organisms, and it is a major component of embryonic development, wound healing, and immune responses. Chemotaxis involves a complex cascade of events--formation of signaling complexes, receptor polarization, adhesion molecule activation, and cytoskeletal reorganization. Previous assay methods were limited in several ways that reduced users' abilities to obtain quantitative data or to control conditions precisely. We describe a unique chemotactic assay that can incorporate multiple chemotactic gradients in different spatial and temporal combinations. In addition, this assay is easily adapted for live-cell imaging and fluorescent microscopy. With its relative simplicity, flexibility, and precision, this method is a key tool for the study of cellular chemotactic responses and the signaling processes underlying them.

Hypersensitivity to metallic biomaterials: a review of leukocyte migration inhibition assays

Metal hypersensitivity is a well-established phenomenon occurring in a variety of domestic and workplace settings. Degradation products of metallic biomaterials may mediate metal hypersensitivity. However, little is known about the short- and long-term pharmacodynamics and bioavailability of circulating metal degradation products in vivo. Mechanisms by which in vivo metal sensitivity reactions occur have not been well characterized and the degree to which metal sensitivity may be a predisposing factor for eliciting an overaggressive immune response remains clinically unpredictable. In vitro leukocyte migration inhibition assays have been used for investigating cell-mediated hypersensitivity reactions to biomaterial and biomaterial degradation products. This review provides a historical and technical summary of four in vitro techniques used for determination of leukocyte migration activity: (1) membrane migration or Boyden chamber, (2) capillary tube, (3) leukocyte migration using agarose technique, and (4) collagen gels. It is difficult to determine which, if any, of these techniques is singularly best suited for the investigation of suspected biomaterial-related symptoms in patients. However, Boyden chamber membrane migration testing is recommended for clinical investigations, principally because a high degree of standardized investigator independent materials and methodologies is necessary for compiling and comparing the results of patients tested at various times over the length of an extended study. Ultimately, in vitro migration inhibition testing has the potential to provide a reliable means for predicting some complications and thus enhancing the outcome for patients receiving metallic implants. Continuing improvements in migration inhibition testing methods, used alone or in combination with other immunologic assays, will likely improve assessment of patients susceptible to biomaterial antigen-induced delayed-type hypersensitivity responses.

Phototoxicity of tetracyclines as related to singlet oxygen production and uptake by polymorphonuclear leukocytes

The photo-induced singlet oxygen production of six tetracyclines was measured as tryptophan degradation. Demethylchlortetracycline was the most efficient singlet oxygen producer followed by doxycycline. The least efficient producer was minocycline. Doxycycline, however, was the most potent inducer of photodamage to polymorphonuclear leukocytes (PMNLs) followed by demethylchlortetracycline. Accordingly, the singlet oxygen production during irradiation did not correlate with the induction of photodamage to the PMNLs. However, the uptake of doxycycline by the cells was 3 times higher than that of demethylchlortetracycline, and the tetracycline-induced photodamage to the PMNLs correlated with the product of singlet oxygen production during irradiation and the drug uptake by the cells.

Inhibition of human leukocyte metabolism and random mobility by local anaesthesia

Hexose-monophosphate shunt (HMS) activity, myelo-peroxidase-(MPO)-mediated iodination and random mobility in human polymorphonuclear leukocytes (PMNs) were studied in the presence of lignocaine. Incubating the PMNs with 0.1% lignocaine during phagocytosis inhibited the 14CO2 produced from glucose-1-14-C via the HMS shunt by 33%. On increasing the concentration of lignocaine, a dose-dependent inhibition was noted. The MPO-mediated iodination was inhibited by 73% in the presence of 0.1% lignocaine, and complete inhibition took place when the concentration was increased to 0.5%. The random mobility of leukocytes was studied by an opto-electronic technique. In the presence of 0.5% lignocaine, all leukocytes examined were completely immobilized; in the presence of 0.1% lignocaine immobilization took place within 45-65 min.

In vitro effect of the slime of Pseudomonas aeruginosa on the function of human polymorphonuclear neutrophils

The slime of Pseudomonas aeruginosa markedly impaired the in vitro motility, endocytosis, and phagosome formation of normal human polymorphonuclear neutrophils. This profound impairment of neutrophils, although without alteration of their viability, may contribute to the virulence of this microorganism.

A rapid technique for measuring leukocyte chemotaxis in vivo

A modification of connective tissue air bleb technique was used to develop a model system in inbred strains of mice for the study of chemoattractants in vivo. The method was developed using the well characterized n-formylated chemotactic peptide, f-Met-Leu-Phe, as the positive control. Injection of 0.1 ml of f-Met-Leu-Phe solutions from 10(-7) to 10(-10) M resulted in an influx of polymorphonuclear leukocytes within 2 h. Study of the kinetics of the response showed that the number of infiltrating cells reached a peak within 8 h and slowly declined over a 2-day period. The predominant infiltrating cell type during the first 24 h was the polymorphonuclear leukocyte. Between 24 and 48 h the polymorphonuclear leukocytes were replaced by monocytes. By utilizing an inbred mouse strain (DBA-1J and 2J) sufficient or deficient in C5 it was possible to distinguish compounds that were directly chemotactic from those that worked indirectly, or whose chemotactic potential could be enhanced by generation of the chemotactic complement split product C5a. The method was found to be technically simple, reproducible and semi-quantitative and represents a good model system to facilitate the comparison of chemotactic responses in vivo and in vitro.

Influence of tetracyclines on human polymorphonuclear leukocyte function

Low concentrations of oxytetracycline, doxycycline, or minocycline (less than 10 micrograms/ml) did not influence in vitro polymorphonuclear leukocyte random migration, chemiluminescence, or glucose oxidation. At high concentrations of doxycycline or minocycline (greater than 10 micrograms/ml), chemiluminescence and glucose oxidation were impaired. High concentrations of doxycycline also reduced random migration. Oxytetracycline did not influence these functions in concentrations up to 100 micrograms/ml. The inhibiting effect of doxycycline and minocycline was abolished when 4 mM Mg2+ was added to the reaction mixture, and 4 mM Ca2+ partly restored minocycline-inhibited polymorphonuclear leukocyte functions. This indicates that the major effect of tetracyclines on in vitro polymorphonuclear leukocyte functions is mediated by their divalent cation chelating effect and that the results of in vitro experiments are highly dependent on the concentration of divalent cations in the reaction mixtures. The difference between the tetracyclines may be due to differences in lipid solubility, with solubility being highest for minocycline and lowest for oxytetracycline, or to different divalent cation chelating ability.

Granulocyte function in malignant monoclonal gammopathy

Granulocyte function was studied in 22 patients with untreated myelomatosis or macroglobulinaemia. Granulocyte adhesiveness (GA) and migration in capillary tubes (Tm) were, except for light chain disease, significantly decreased in patients of all gammopathy classes especially IgG myelomatosis. A plasma factor inhibited GA. The impairment of Tm was due to an inhibiting factor as well as lack of a stimulating plasma factor. Migration of granulocytes to skin chambers was decreased in patients with IgG myelomatosis. Chemiluminescence production during phagocytosis of opsonized zymosan was decreased. Compared to control sera, the opsonic activity of patient sera was strongly decreased. The impaired granulocyte functions in patients with malignant monoclonal gammopathy may contribute to the enhanced susceptibility to infections in these patients.

A new assay for leukocyte chemotaxis using cell retrieval, electronic particle counting and flow cytometry

A new micropore membrane assay for leukocyte migration has been devised. It permits the complete retrieval in monodisperse suspension of functionally intact cells that have traversed the membrane, thus allowing the application of precise, automated techniques, including flow cytometry and electronic particle counting. Hemocytometers may also be used. Direct comparison with 2 different conventional membrane methods showed that the new method performed superiorly. It was also much more economical with regard to time and labor. This technique permitted detection of functional differences between leukocytes isolated from blood in different ways. Data on the duration of concentration gradients in chemotaxis chambers are also presented.

Polymorphonuclear functions and aging in humans

To determine whether normal aging interferes with the functional capability of polymorphonuclear leukocytes (PMNs), 6 tests of PMN function were performed in 285 healthy subjects whose ages ranged from 20 to 97 years. A second selection based upon blood measurement and a review of medical histories 6 months later, eliminated 68 subjects. The 217 remaining persons were sub-classed by age into 7 groups including equal numbers of males and females. The functional properties of PMNs in the aged, when compared to those of younger adults, were characterized by: (a) a decrease in the chemotactic response in the 80+ age group: (b) increased adherence, with onset after age 70, maximal after age 80; (c) a progressive decrease of NBT dye reduction capability, up to age 70-79, followed by an unexplained increase of the mean value after age 80; (d) diminished Candida-killing activity, appearing in the 60+ group and becoming lowest in the oldest group; and (e) lack of changes in spontaneous migration and endocytosis. The mechanisms by which this impairment occurs are hypothetical. It is proposed that normal PMNs, after leaving the bone marrow, are influenced by various humoral components such as metabolic byproducts or immune processes altered by aging. Thus the defective PMN may represent only another victim of the aging process.

In vitro effect of tobacco smoke components on the functions of normal human polymorphonuclear leukocytes

The function of polymorphonuclear leukocytes (PMNs) has previously been shown to be impaired in smokers in comparison with healthy nonsmokers. Potent inhibition of PMN chemotaxis has been achieved with whole tobacco smoke, the gas phase of smoke, and a water-soluble extract of whole smoke. In the present work several aspects of PMN function were studied after exposure to water-soluble fraction of the particle phase of tobacco smoke collected on glass fiber filters. These tests included capillary tube random migration, chemotaxis under agarose, phagocytosis of yeasts, Nitro Blue Tetrazolium dye reduction, and whole-blood bactericidal activity. The water extract of the particle fraction of smoke had a high content of nicotine when compared with the levels achieved in plasma of smokers and a much lower concentration of aldehydes when compared with the gas phase of smoke. It had no cytotoxic effect and did not affect phagocytosis, oxygen consumption, or bactericidal activity. Nitro Blue Tetrazolium reduction of both resting and stimulated PMNs was significantly decreased only with the most concentrated solution. The tested solutions exerted a dose-related depressive effect on capillary tube random migration, whereas the random migration measured in the agarose chemotaxis test was normal. Nevertheless, the chemotactic response to a caseine solution was significantly decreased. The same tests were performed in the presence of several concentrations of a nicotine solution and the only test to be affected was the capillary tube random migration, and, that only at a very high concentration. The results of this study contribute to the more precise delineation of the extent of the dysfunction of PMNs exposed to tobacco smoke components and indicate that deleterious products are released from the particle phase of the smoke, which deposits all along the respiratory tree.

Kinetics of locomotion of human granulocytes in a double-filter system. Effect of activating plasma with zymosan and casein

A new modification of Boyden's millipore filter technique is described in which leukocytes are sandwiched between two filters and allowed to migrate in two directions. This technique offers a better basis for comparison with mathematical models than does single filter methods. Using this technique, casein in low concentrations was leukokinetic in the absence of plasma, but did not show leukotactic activity unless plasma was present. Zymosan-activated plasma was leukokinetic and strongly leukotactic.

A 48-well micro chemotaxis assembly for rapid and accurate measurement of leukocyte migration

We designed a 48-well chemotaxis chamber to minimize manipulation time and amount of material required by the larger blindwell or Boyden chemotaxis chamber. Cell and chemoattractant dose-response curves showed that results were comparable to our better than those obtained with blindwell chambers. The volume of chemoattractant per well is 25 microliter; the number of cells can be as low as 10,000. The time needed for setting up this multiwell unit and for staining the membrane filter sheet is negligible. Combined with the use of an image analyzer to count the number of migrated cells, the method is suitable for clinical research on the functional state of monocytes in large groups of patients.

Assessment of neutrophil chemotaxis and random migration in childhood. Comparison between leading-front and lower surface count methods

Neutrophil chemotaxis and random migration were studied in 65 healthy children and 18 normal adults. The method used, the leading-front technique, was more accurate and reproducible than the lower surface count method. Chemotaxis in children under 15 years differed from that in adults. This age effect was most pronounced in those less than 6 years, and particularly in those less than 2 years. When investigating chemotaxis in childhood, comparisons with age-matched controls should be made.

A semi-automatic method of measuring leucocyte movement

A semi-automatic system has been developed for measuring the migration of leucocytes within a micropore filter. The distance in micrometers is displayed digitally or analysed on-line by a digital computer. These improvements have resulted in considerable saving in time, permitting the full potential of the micropore method to be utilised. To illustrate this technique we report results from experiments to measure dose-response relationships of leucocytes to casein and the variation in response to Staphylococcus aureus and casein of cells from normal human subjects.

Effect of tobacco smoking on the functions of polymorphonuclear leukocytes

Eight tests investigating the function of circulating polymorphonuclear leukocytes were performed in 68 subjects, half of whom smoked at least 20 cigarettes per day. Comparison of the two groups allowed determination of the in vivo effect of tobacco smoke on the nonspecific defense system of the body. Ingestion ability, oxygen consumption, and bactericidal activity were normal in smokers. Myeloperoxidase and neutrophil alkaline phosphatase activities also were unchanged. The nitroblue tetrazolium reduction and the serum lysozyme levels were slightly increased in smokers. The capillary tube random migration, though, was depressed, and intensive smoking further aggravated this change. It is suggested that tobacco smoke acts directly on one (or several) unidentified target site of polymorphonuclear leukocytes. This impairment, demonstrated in vivo, probably plays a role in the genesis of the bronchopulmonary diseases so frequent in heavy smokers.

Polymorphonuclear neutrophil chemotaxis under aerobic and anaerobic conditions

The motility of human polymorphonuclear neutrophils was studied in vitro under aerobic and anaerobic conditions. Chemotactic factors were generated from plasma with immune complexes or with whole bacteria (Staphylococcus aureus, Escherichia coli, and Bacteroides fragilis). Chemotaxis induced by chemotactic factors generated from immune complexes was identical under both conditions. However, chemotaxis utilizing chemotactic factors generated from bacteria was markedly depressed under anaerobic conditions. Mean random tubemoltility was not significantly different under aerobic and anaerobic conditions. These data indicate that different metabolic pathways may be involved in polymorphonuclear neutrophil movement. Some of these pathways require oxygen (chemotaxis in response to factors generated by bacteria in plasma), whereas others do not (random tube migration and chemotaxis in response to factors generated by immune complexes in plasma). These observations may be important in the induction of inflammatory responses within hypoxic tissues.

Leukocyte migration agarose test for the assessment of human neutrophil chemotaxis. I. Effects of environmental factors on neutrophil migration under agarose

To apply the leukocyte migration agarose test (LMAT) to the in vitro assessment of human neutrophil chemotaxis, effects of different culture conditions on neutrophil migration under agarose were studied. Presence of either serum or human serum albumin (HSA) in the culture medium was necessary for detectable neutrophil migration. HSA was preferred since heat-stabile chemotactic agents were found to be generated from fresh serum in the presence of agarose. Additional CO2 in the assay milieu could be replaced by decreasing the NaHCO3 concentration of the culture medium. Both the directed and the spontaneous migration rates of neutrophil leukocytes increased when the concentration of agarose was decreased. Area and distance of migration and cumulative cell count of migrated neutrophil leukocytes were suitable for quantitating the neutrophil migration rate.

Leukocyte migration agarose test for the assessment of human neutrophil chemotaxis. II. Variables in the attraction assay

Optimal conditions for the attraction assay of human neutrophil leukocytes were studied, using the leukocyte migration agarose test (LMAT). Larger migration areas were obtained toward the attractant wells when they were filled with zymosan-activiated serum (ZAS) in advance than when both the attractant and the cells were added simultaneously. Chemotactic indices (CI; the ratio between the migration rate toward attractant and that toward the control substance) decreased when the number of applied neutrophil leukocytes increased, whereas migration differentials (MD; the difference between the migration rate toward attractant and that toward the control substance) were not markedly affected. Both the spontaneous and the directed migration rates, and CI and MD of neutrophil leukocytes obtained from the same donor on different days varied markedly. When tested repeatedly, however, the neutrophil leukocytes of different donors migrated on the average rather equally toward inactivated serum, as they also did toward ZAS, and the variation of the means of CI and MD was insignificant.

Neutrophil function in bone marrow transplant recipients

The neutrophil function of seven patients receiving allogeneic bone marrow transplantion was studied. Five of the patients had been transplanted for aplastic anaemia and two for acute leukaemia. Determinations were made of neutrophil phagocytosis, chemotaxis, random migration, and microbicidal activity for Candida albicans and Staphylococcus aureus. One patient showed a decreased ability to kill C. albicans at a time when she had active pneumonia due to Pneumocystis carinii. The remainder of the studies showed normal neutrophil functions. No differences were observed in the patients who had graft versus host disease [GvH] from those without GvH. These studies suggest that defects in phagocytic neutrophil function do not contribute significantly to the impaired host defenses in recipients of bone marrow transplantation.

Leukocyte function in familial Mediterranean fever

Neutrophilic leukocytes of patients with familial Mediterranean fever and of normal control subjects were studied in vitro. FMF neutrophils were found to be morphologically normal by light and electron microscopy and to have normal quantities of the lysosomal enzyme lysozyme. FMF cells demonstrated a slight decrease in their ability to migrate randomly in capillary tubes, this was primarily seen in Armenian patients and in those experiencing an acute attack. The leukocytes of these patients functioned normally in regard to their chemotactic and Candida-killing activity.

In vitro adhesion of eosinophils to infective larvae of Wuchereria bancrofti

A reproducible in vitro test was developed to quantitatively study the adhesion of human eosinophils to Wuchereria bancrofti infective larvae. Eosinophils, regardless of the donor, selectively adhered to the larvae in the presence of immune serum. The reaction reached a maximum by 90 minutes at room temperature and remained unchanged up to 6 hours. The adherent eosinophils, however, did not induce any apparent morphologic change in the larvae.

The phenomenon appeared to require, primarily, IgG anti-larval antibodies. Heat-inactivation of the serum did not prevent the reaction from occurring, although addition of fresh normal serum enhanced the intensity of adhesion.

Maximal adhesion of eosinophils was obtained when the larvae were viable and in the presence of immune serum and fresh normal serum during incubation with the leucocytes.

Normal serum was found to induce this adhesion reaction. The responsible factor could be removed by absorption of normal serum with cotton. However, this procedure had no effect on the reactivity of sera from filariasis cases.

The reaction was almost totally inhibited by EDTA and citrate. The anti-inflammatory steroid, betamethasone, had a moderately inhibitory effect. An unexplained finding was an enhancing effect on the reaction when histamine was added to non-reactive normal serum.

Studies on human leukocyte motility. I. Effects of alterations in pH, electrolyte concentration, and phagocytosis on leukocyte migration, adhesiveness, and aggregation

Leukocyte migration was studied in a microhematocrit system which permitted evaluation of the separate effects of leukocyte adhesiveness, intrinsic cell motility, and leukocyte clumping. Leukocyte adhesion to glass required the presence of magnesium ion, was totally independent of calcium ion, and was partially dependent on heat-labile plasma factors. Leukocyte migration was unimpaired by marked acidosis or by wide variations in sodium, potassium, or calcium concentrations. Marked impairment of individual leukocyte motility and increased leukocyte aggregation were observed after phagocytosis of particulate matter, suggesting a mechanism facilitating recruitment and retention of leukocytes at areas of microbial invasion.

Studies on chemotaxis. 3. Modification of Boyden's technique for the evaluation of chemotactic agents

A modification of Boyden's method for evaluation of chemotaxis is described. It permits the measurement of chemotactic agents in serum-free medium. Its possible usefulness for the determination of isolated chemotactic mediator(s) is discussed.

The in vitro action of hydrocortisone on leucocyte migration

Hydrocortisone inhibits the ameboid migration of human leucocytes when added in vitro. The dose-response curve for the reaction between this steroid and leucocytes can be best expressed by a logarithmic plot of the steroid concentrations. Tetrahydrocortisone and desoxycorticosterone had no effect on in vitro leucotyte migration.